Eko and Charlie were supposed to die in the discharge. Their deaths afterward were course-corrections by the universe.
The meant death of Charlie also gave Desmond his ability to see the future, which would eventually get him to see Charlie in the Looking Glass, which would cause Charlie swimming down there and die.
The discharge was caused by a high altitude detonation of Jughead. See the wikpedia page on this phenomenon. When the failsafe key was turned, Jughead was launched into the upper atmosphere. And if Jughead was buried deep underground, a detonation really could destroy the world. The EMP effects of this also explain the loss of communication.
The fail safe causes the discharge, which produces a massive shield (white/violet sky) that eliminates all electromagnetic energy. It is possible that while the discharge takes place, people can leave or enter the island normally, and it can be seen by the outside world: this is backed up by the facts it was picked up on computer screen in the station in the polar region, Michael and Walt are told to leave the island after The discharge by Ben, and the producers hinted that in the season 2 finale we would have an idea of where the season 3 characters would come from - possibly Penelope Widmore, after being contacted by the two men in the polar station, will come to the island with other characters as well.
The fail safe didn't cause these effects at all, its effect is simply to put into place an automated release similar to the manual one of pushing the button. The sky color and noise was caused by the build up of magnetic charge, not by the discharge of it.
This discharge may be related to the October 28 event.
The discharge had nothing to do with electromagnetism but it was a alarm call to the Hanso Foundation that the last working station has stopped.
The discharge noise that was made is the exact noise heard by Mr. Eko in "?", when Eko was talking to Yemi in the Swan. Was Eko to know about the Discharge?
The purple light of the discharge was caused by a redshift of the light from the sun, the result of interaction with the unleashed electromagnetic field.
A discharge can be caused at will by the Others or someone else.
Mikhail saw that the numbers weren't being typed in, so he initiated the discharge to make Locke and the other Losties believe they were responsible.
Why did the others at the pala ferry dock look surprised. Also, why would they do it if they knew it would knock out their sonar beacon.
In the Swan station structure there could've been magnesium or magnesium alloy in use. Recall the metallic wall near the mural, that could've been made of magnesium. During the swan implosion the magnesium could've ignited from a blast in the bunker resulting in the bright light.
The noise could be started by a separate cause all together, such as the magnet growing to high strengths and then the final deactivation of the magnet, resulting in the implosion.
Kelvin says that after the incident the electromagnetism builds up and has to be released by pressing the button. I reckon that it would have run out eventually but turning the fail-safe key caused all the remaining electromagnetism to be released in one huge discharge. The huge amount of electromagnetism released caused the sky to go purple.
What happens to the Swan during the discharge is what could have happened in the Orchid station video when the rabbit they were using for their time travel experiments inexplicably showed up at the same point in time. In the video, Dr. Chang seemed greatly disturbed that the rabbit and its time traveling self were both in the present and ordered that the two be kept separate. Judging by his tone and his apparent concern, the two rabbits together would have caused a problem. Well, the problem that would have been caused by the rabbits being together, IS what actually occurs at the Swan. Essentially the fail safe causes a slight rift in time causing two versions of the Swan to occupy the same place at the same time. And since the same object can't physically occupy the same place at the same time twice, it essentially merges into itself causing some unique form of implosion and basically disintegrating into itself. When Hurley describes the sound it makes like a "blender", this is actually very accurate, as the Swan is essentially blending into itself. This is why there is only a crater left where the swan used to be, and seemingly no debris besides that quarantine door. And in the case of the quaratine door, it was probably removed, so when the time jump occured, it didn't actually blend into self, and instead was just launched into the air by the shockwave. And those inside the swan managed to survive because they didn't merge into themselves due to not being in the exact same spot in the other version of swan that merged into the present version of the swan (or alternatively, whatever version of the swan the present version of the swan merged into...the time jump was probably very slight either way..because technically for the furniture and other contents of the swan to disintegrate too, they would need to be occupying the exact same spot at both points in time). Additionally, this event also causes the island to cease moving physically, which is why Ben starting jamming the signals on the island so as to keep the islands location hidden. Because without the ability to move, the only way to keep the island safe is to try and keep it hidden. This may even be further confirmed based on how long the freighter was able to remain in the vicinity of the island. However, turning the wheel in the cave under the Orchid restarts the process of moving.
The computer was used to prevent the sky from turning purple. This much we know. But why do that? As long as the Swan was operational and the computer was used to discharge the EM build up, the island could not be moved. The DI had a vested interest in keeping the island stationary because it could not be detected any other way. This is why Ben came to the hatch in the first place, to manipulate the Losties into destroying the computer.
The purple sky is the snowglobe solidifying to protect the Island while it moves.
Will directly/indirectly lead to the discovery of the island and/or the rescue of the castaways. Locke says he "Saved us all" after smashing the computer in The Swan.
The White Sky was caused by the destruction of the electromagnetic shield which protects the island from outsiders, acts as a cloaking device to navigation/discovery satellites and keeps the inhabitants on the island. The fail-safe destroyed that shield/defence mechanism and thus the island will now be visible/discoverable and escapable. The two men in the final scene of the finale picked up the destruction of the electromagnetic field and are on their way to the island. It is also probable that the island will be discovered by other people as it would appear on other navigation systems.
The discharge may have turned the sky purple and lit up the sky because the discharge caused an auroral effect.
The color of the sky is also somewhat similar to that caused by Cherenkov radiation (caused when particles pass through a medium - in this case, air - at a speed greater than the speed of light in that medium, altering the medium's electromagnetic field).
The discharge was not an explosion, but just that - a magnetic "discharge." No pyrotechnics were in evidence, and this would still explain the (ferrous) hatch door falling into the camp. (See also: Gauss gun).
The discharge may be an Electromagnetic Pulse (EMP). If it is, it will most likely render all unshielded electronics on the island useless.
Desmond appears to have known about Locke's speech before he made it. Perhaps the discharge either gave him precognitive abilities or it warped time briefly giving him a glimpse of the future.
There is substantial reason to believe that the island's healing powers are related to its electromagnetism (in S.O.S, the faith healer Bernard takes Rose to tells her that his compound is located around the site of unique electromagnetic activity which is responsible for his "ability" to heal through faith. He further states that particular site could not help Rose, but there may be another elsewhere on Earth which could heal her), there is no evidence to suggest that The Swan was the source of the electromagnetic anomaly on the island. Rather, it is more likely that one of DHARMA's projects was related to harnessing that power in some way, through the construction of the "electromagnetic wall" that eventually cracked and had to be discharged to prevent the electromagnetic charge from building up to destructive levels. In other words, the island's electromagnetic properties are a naturally occurring anomaly, and part of The Swan's structure and mandate were to study and find applications for it. Hence, destroying the hatch would have no effect on the island's healing properties, as the natural anomaly would still exist.
After the discharge, The Others may have lost their contact with the outside world. In "Not in Portland", when Jack asks Tom why they didn't take Ben to a doctor off the island, Tom replies but is cut-off mid sentence by Ben's awakening, saying only "ever since the sky turned purple--". This could suggest The Others can no longer communicate with off-island contacts, and thus, can not transport Ben off the island. This theory supports the theory claiming the discharge is an Electromagnetic Pulse, which may have rendered all communication devices useless.
This is contradicted by the fact that the Others continue to use short-range walkie-talkies and other unshielded electronic devices (the bear cage shocker, Room 23, and monitoring equipment in The Hydra, for example) that would be disabled by an EMP.
The effects of an EMP are temporary on most electronic devices, not permanent.
The biggest exception being computer systems, which is odd considering that the computer at The Flame still functioned after the discharge.
EMPs also affect various electromagnetic frequencies, depending on the method of deployment. More research into the actual effects of EMPs is needed, as those effects are still not widely understood in the real world.
Electromagnetic wall in the Swan had positive or negative magnetic field. When the hatch imploded some items had the same pole, so they were ejected away from the hatch (like Locke, Eko, Charlie, Desmond, his photograph, and several other items.
Caused The Flame's communications systems to stop working.
The very bright light due to the discharge was created by the earth's flux lines being perpendicular to earth which resulted in unfiltered solar radiation hitting the island. The discharge created a hole in the earth's magnetic field, resulting in "polar rain".
Unlikely, since the Earth's magnetic field deflects only charged particles, rather than the visible wavelengths of light. In other words, even if the Earth's magnetic field were to be affected in this way, it would not result in a change in the color/intensity of the sky, since our eyes cannot "see" outside of the visible range of light.
If this were the case, the exposure the islanders would have had to the intense solar radiation, even though for a short period of time, could have consequences on their general health, i.e. radiation poisoning.
However, the pink color observed is suggestive of the spectral emission lines of the atmosphere (primarily the faint pinkish line from oxygen) and might be explained in terms of atmospheric ionization.
It seems possible that the purple color of the sky was the result not of particles or waves transmitted from the Swan, but perhaps waves reflected back towards it after hitting the magnetosphere or a reflective layer of the atmosphere. This could be an aurora from the opposite direction, and the purple color of the sky could reflect this - since the waves would be bouncing back with a given frequency, if an interaction occurred to make the waves visible they would appear blue-shifted on their return bounce towards the island.
The discharge caused the inhabitants of the Hatch to be transported in time and space slightly, avoiding the explosion.
The island itself stops moving, which is why Ben had to jam all the signals to be able to keep the island hidden at its current location. This is also why Christian told Locke he needed to move the island to get away from the freighter, because the island itself was no longer doing it automatically.
Discharge NOT caused by Failsafe
The failsafe didn't cause the discharge at all, but merely imploded the station to destroy or diffuse what was behind the swans wall. The flash was the island pulling Desmond out of the station to safety because the island is not done with him. Behind the wall- I think the hostiles buried Jughead, but by the time DHARMA shows up the strange matter on the island causes the radioactive material in the bomb to start acting in strange ways, so they built a station next to it to study the phenomenon. Unfortunately the 'incident' cause some unexpected changes in the bomb forcing them to pour a much larger concrete wall and put in place the protocol.
I recently stumbled across Warrens Ellis' comic New Universal, published by Marvel, which features an occurrence called the white event, in which the earth was bathed in a mysterious blinding flash of light, and thereafter many people began to develop paranormal powers. I cant help but feel that is all very familiar.
In 1984 DC's Crisis on infinite Earths, a mysterious event starts to make the mutliverse collapse and return to oblivion. A white wall of anti-matter erases everything while a mysterious being on a space station tries and plants giants forks that are supposed to fuse the multiple versions of Earth. Before the wall erases a world, the skies turn to red and violent rain falls. Also, dark beings nearly invicible attack the heroes. This story is highly connected to Green lantern and The Flash, the last experiencing future sightings.